This research is concerned with the elaboration and evaluation of preventive measures with high risk children of psychotic parents. The study focuses on three aspects of intervention: 1) The effect on the vulnerabilities of the children (assessed in a primary project) of counter-measures directed specifically at the factors of vulnerability as compared with "classical" interventions having more global aims (individual and group psychotherapy); 2) The effect on the disorganization of the families (assessed in a primary project) of counter-measures directed specifically at the factors of disorganization as compared with "classical" interventions with more global aims (family therapy, parental counselling, casework with the family); 3) The effect of family therapy based on complete psychological portfolios on every family member in mitigating the credulous acceptance of delusional and hallucinatory ideas, correcting incongruities of affect and communication, and diminishing magical and superstitious systems of belief. The risk entailed in this group of children stems from an amalgam of diathetic and environmental influences; the preventive measures are directed at the presently healthy child at risk, the child manifesting transient micro-antecedents of adult psychosis, the child with "contact" disturbances resulting from close and constant exposure to psychosis, and the child reacting non-specifically to the general disadvantages of the environment. To what extent these measures have any primary preventive effect on the emergence of adult psychosis (genetic expectation: 17% of the experimental sample) only an eventual follow-up will disclose. It should be emphasized that these are among the most extensively and carefully studied children, so that a follow-up would seem to be almost mandatory in the next ten to twenty years.